Authors of section

Author

Tomas Guerrero

Executive Editor

Amy Kapatkin

General Editor

Noel Moens

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Parallel K-wires

1. Principles

The preferred treatment for 31-B2 physeal fractures of the femoral head is internal fixation with parallel K-wires. The use of K-wires avoids compression of the growth plate and minimizes the risk of premature closure.

Unlike cervical or basicervical fractures, Salter-Harris type I fractures of the femoral head are generally stable after reduction. This is due to the “L” shaped physis and its proximity to the point of application of the weight bearing forces.

In animals with minimal growth potential left, this fracture can also be repaired using a screw in lag fashion and anti-rotational K-wires.

parallel k wires

2. Patient positioning

This procedure is performed with the patient in either lateral recumbency....

lateral recumbency position

3. Approach

This type of fractures can be treated using a craniolateral approach,

lag screw and k wire

4. Surgical technique when using a craniolateral approach

Introduction

Anatomical reduction of the fragments is mandatory for the correct placement of the K-wires.

The femoral head remains in the acetabulum due to its attachment to the ligament of the head of the femur, while the femoral neck is displaced cranial and dorsally.

If parts of the joint capsule remain intact, the displacement may be minimal.

parallel k wires

K-wire insertion in the femoral neck

The K-wires are started at a point slightly distal and just cranial to the third trochanter. The wires are directed dorsally and slightly cranially to follow the direction of the femoral neck and avoid the trochanteric fossa.

lag screw fixation

Reduction

To reduce the fracture, the femur is distally retracted, derotated, and slid caudally into the matching surface of the femoral head.

parallel k wires

Stabilization

The pins are driven into the femoral epiphysis.

Note: Care is taken to avoid penetrating the articular surface. The visible portion of the articular surface is visualized by applying gentle lateral traction on the femur to open up the joint space. The non-visible part of the articular surface can be palpated using a small curved instrument like a curved hemostatic forceps or a Freer periosteal elevator.

Pins protruding through the articular surfaces are retracted below the level of the cartilage.

parallel k wires

The lateral ends of the pins are bent and cut short.

parallel k wires

5. Surgical technique when using a ventral approach

Reduction

The fracture is reduced by distal distraction of the femur and its gentle manipulation.

parallel k wires

Stabilization

One K-wire is inserted through the fovea capitis femoris with a low speed power drill towards the third trochanter.

parallel k wires

A second pin is inserted cranially to the first one and directed laterally.

parallel k wires

Both pins are cut and countersunk below the level of the articular cartilage.

parallel k wires

6. Surgical technique when using MIO

Introduction

Minimally invasive osteosynthesis can be used to treat capital physeal fractures using K-wires. The use of fluoroscopy is mandatory to ensure adequate reduction and K-wire placement. Preservation of blood supply is an advantage of using this method.

Reduction

Reduction is performed in a closed manner and visualization is done via fluoroscopy.

Fixation

The pins are positioned percutaneously from lateral to medial into the femoral head under fluoroscopic visualization.

parallel k wires

7. Validation of fixation

Postoperative orthogonal radiographs are taken to assess fixation.

8. Case example B2

6.5-month-old Central Asian Shepherd dog with a B2 fracture from being hit by a car.

parallel k wires

The fracture was repaired using three stacked intramedullary pins passed from the femur just distal to the third trochanter into the femoral head. Good reduction and alignment of the capital physeal fractures and sacroiliac luxation.

parallel k wires

9. Case example Salter-Harris type I

6-month-old Norfolk Terrier with a Salter-Harris type I physeal fracture of the femoral head and fractures of the left iliac wing, pubis and ischium car.

parallel k wires

The Salter-Harris type I fracture was repaired from a ventral approach, using two K-wires of 1mm diameter. One K-wire was seated in the fovea capitis femoris and the second cranial to it and countersunk. The round ligament was not transected.

parallel k wires

Postoperative radiographs at 1 month.

parallel k wires

Postoperative radiographs at 26 months. Note the narrowing of the femoral neck (“apple coring”), likely resulting from damage to the blood supply from trauma or surgery.

Reference: Guerrero TG, Koch D, Montavon PM. Fixation of a proximal femoral physeal fracture in a dog using a ventral approach and two Kirschner wires. Vet Comp Orthop Traumatol 2005; 18: 110-3

parallel k wires

10. Aftercare

Activity restriction is indicated until evidence of bone union is detected on radiographic examinations.

Implants may cause discomfort of the adjacent soft tissue. If this occurs, implants are removed after radiographic evidence of bone healing is complete. In case of infection, implants must be removed after complete bone healing.

Phase 1: 1-3 day after surgery

Aim is to reduce the edema, inflammation, and pain.

Integrative medical therapies, anti-inflammatory and analgesic medications.

Phase 2: 4-10 days after surgery

Aim is to resolve the hematoma, edema and control pain, and prevent muscle contracture.

Anti-inflammatory and analgesic medications may still be needed. Rehabilitation and integrative medical therapies can be used.

Special attention should be given to patients less than 1 year of age with a femoral fracture. Rehabilitation is strongly recommended to help prevent quadriceps muscle contracture.

If the dog is not starting to use the limb within a few days after surgery, a careful evaluation is recommended.

10-14 days after surgery the sutures are removed.

Radiographic assessment is performed every 4-8 weeks until complete bone healing is confirmed.

Implant removal

If there is no implant failure or infection, there is no need for implant removal.